In-band signaling of access network information along the user-plane for differentiated charging

ABSTRACT

Techniques are provided to inform a mobile packet core of the access network/radio access technology (AN/RAT) change with the use of in-band signaling along the user plane and hence reduce signaling between radio access network and mobile packet core network. A new extension header content is defined to signal the AN/RAT change information, Cell Group changes and acknowledging the same. Further still, a method is provided to handle AN change notification for split bearer scenarios by introducing a split bearer flag for the mobile packet core to be notified of the predominant access type serving the subscriber data session in 5G Non-Stand Alone (NSA) Option-3, Option-3A and Option-3X, so that static or dynamic configurations can be applied by the mobile core network accordingly.

TECHNICAL FIELD

The present disclosure relates to mobile network communications.

BACKGROUND

Many incumbent mobile service operators are deploying fifth generation(5G) as Non-Stand Alone (NSA) with fourth generation (4G) Control andUser Plane Separation (CUPS). NSA leverages the existing Long TermEvolution (LTE) radio access and Evolved Packet Core (EPC) to anchor 5GNew Radio (NR) devices using the Dual Connectivity (DC) feature. NSAOption-3X is a widely accepted deployment option where the radio accessnetwork is composed of a 4G eNB as the master node and a 5G gNB as thesecondary node. Deployments of 5G gNB are spotty and not contiguousacross a large geography.

A DC-enabled User Equipment (UE) first registers for mobile data servicewith the 4G EPC network. Based on an UE measurement report, the 4G eNBcommunicates with the 5G-NR gNB and enables the UE to simultaneouslyconnect to the 4G and 5G networks. This allows the Radio Access Network(RAN) to move one or more UE bearers seamlessly between different accesstypes (Evolved Universal Terrestrial Radio Access Network(EUTRAN)/LTE/4G and NR/5G).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an access network handoversituation for Dual Connectivity-enabled user equipment for whichsolutions are presented herein.

FIGS. 2A and 2B illustrate diagrams of a user plane extension headerused to signal information relevant to an access network handover,according to an example embodiment.

FIGS. 3-5 illustrate operational diagrams for different scenarios of aDual Connectivity-enabled user equipment in which the extension headeris used for signaling access network changes, according to an exampleembodiment.

FIG. 6 is a detailed call flow diagram depicting operations for accessnetwork change reporting, according to an example embodiment.

FIG. 7 is a detailed call flow diagram depicting operations that involvethe access network change notification and acknowledgment signaledin-band, according to an example embodiment.

FIG. 8 is a flow chart depicting operations performed by a radio accessnetwork element, according to an example embodiment.

FIG. 9 is a flow chart depicting operations performed by a control planegateway element in a mobile core network, according to an exampleembodiment.

FIG. 10 is a hardware block diagram of a computing device that may beconfigured to perform the techniques presented herein, according to anexample embodiment.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

In accordance with an example embodiment, techniques are provided toinform a mobile packet core of the access network/radio accesstechnology (AN/RAT) change with the use of in-band signaling along theuser plane and hence reduce signaling between radio access network andmobile packet core network. In one form, a method is provided for use ina communication system that includes at least a first radio accessnetwork of a first radio access technology type and a second radioaccess network of a second radio access technology type. The method isperformed at a radio access network element of the second radio accessnetwork, and comprises receiving a data transmission from a userequipment that has dual connectivity capabilities for communication inboth the first radio access network and the second radio access network.The method includes determining whether there is a change in radioaccess technology type for the user equipment indicating that the userequipment has handed over from the first radio access network to thesecond radio access network. The method further includes, based on thedetermining, encapsulating data from the user equipment in a packet thatincludes a header comprising an indication whether there is a change ofradio access network, to form an encapsulated packet. The method furtherinvolves sending the encapsulated packet to a mobile core network.

In another form, a method is provided that is performed at a gatewayelement in the mobile core network. The method includes obtaining anencapsulated packet representing a data transmission sent by a userequipment that has dual connectivity capabilities for communication inboth the first radio access network and the second radio access network.The encapsulated packet includes a header that indicates whether thereis a change in radio access network for the user equipment. The methodinvolves evaluating the header of the encapsulated packet. The methodincludes determining whether there is a change in radio access networkfor the user equipment based on the evaluating. The method involvesforwarding the encapsulated packet to a user plane entity in the mobilecore network.

Example Embodiments

E-UTRAN and New Radio, Dual Connectivity (EN-DC) technology enables theintroduction of 5G services with higher data rates and othercapabilities. This approach permits service providers to roll out 5Gservices on existing 4G core networks with NSA capabilities.

Reference is first made to FIG. 1. FIG. 1 shows a mobile network 100that includes a mobile core network 105 having a Policy and ChargingRules Function (PCRF) 110, an Online Charging System (OCS) 115, a SystemArchitecture Evolution Gateway (SAEGW) 120, and a Mobility ManagementEntity (MME) 130. The PCRF 110 and OCS 115 may manage Policies and Quotafor User Equipment (UE) subscribers/users. FIG. 1 shows a UE 160, as anexample.

FIG. 1 shows a RAN 170 that is based on a first access network type,such as 4G/LTE access network (AN). RAN 170 includes, in anoversimplified form, an evolved NodeB (eNB) 172. In addition, FIG. 1shows a RAN 180 that is based on a second access network type, such as5G/NR AN. The RAN 180 includes, in an oversimplified form, nextgeneration NodeB (gNB) 182. UE 160 has EN-DC capabilities such that itcan connect simultaneously to eNB 172 and to gNB 182. eNB 172 is alsoreferred to as an LTE Master Node eNB (MeNB). In addition, gNB 182 isalso referred to as a Secondary Node gNB (SgNB).

The interfaces between the various entities shown in FIG. 1 areindicated as such by name in the figures. There is an S1-MME interfacebetween MME 130 and eNB 172. There also is an S1-U interface betweenSAEGW 120 and eNB 172, and between SAEGW 120 and gNB 182. There is an X2interface between eNB 172 and gNB 182.

It should be understood that the RAN 170 and RAN 180 may be based ondedicated physical entities, such as eNBs and gNBs, or may beimplemented as virtualized RANs (vRANs), including disaggregated vRANs.The eNB 172 and gNB 182 may be disaggregated in a vRAN architecture intodifferent vRAN components.

In some instances, a vRAN architecture can be implemented as adisaggregated vRAN architecture that includes the split of a basestation, such as an eNB or a gNB, into a Central (or Centralized) Unit(CU), one or several Distributed Units (DUs), and one or several RadioUnits (RUs). Further disaggregation may include separation of the CUinto a Central Unit Control Plane (CU-CP) component and a Central UnitUser Plane (CU-UP) component. In some instances, certain vRAN componentsmay also be referred to as virtualized components (e.g., virtualized DU(vDU) components, and/or virtualized CU (vCU) components). For a vRANarchitecture, one or more RU(s) can interface with a DU component, whichfurther interfaces with a CU-CP component and a CU-UP component. In someinstances, such as for shared cell vRAN architectures, multiple DUs(each interfacing with corresponding RU(s)) can interface with a CU-CPcomponent and a CU-UP component.

NSA Options, such as Option-3, Option-3A and Option-3X which related toLTE-Assisted options for EN-DC scenarios, have been developed to dealwith various ways that mobile network operators may evolve betweendifferent access network technologies in their deployments. In Option 3,there is no connectivity from the gNB 182 to the mobile core network105. In Option-3A, the gNB 182 has an S1-U interface to the mobile corenetwork 105, but no X2 interface to the eNB 172. In Option-3X, the gNB182 has an S1-U interface to the mobile core network 105 and an X2interface to the eNB 172. The techniques presented herein are applicableto Option-3, Option-3A and Option-3X.

Split bearer is a functionality that allows instantaneous traffic flowswitching between E-UTRAN and NR without having to switch the S1-U endpoint in the 5G NSA Option-3X Architecture. Handover across an accessnetwork, such as between 4G and 5G, will not trigger any signalingtowards the mobile packet core network.

Use cases, such as differentiated charging based on AN, cannot beimplemented if the mobile packet core network is not aware of theserving access network. In addition, there is a need to handle scenarioswhere the bearer is split at the Packet Data Convergence Protocol (PDCP)layers, such as when both the Radio Link Control (RLC) layer and PDCPlayer are serving different radio Access Technologies (RATs). Forexample, the S1-U (PDCP) is anchored at a secondary gNB (SgNB) and theUE is served by the Master eNB (MeNB) radio through the X2 interface.This is described further below in connection with FIG. 6.

In the current 5G NSA Option-3X deployments, secondary node (gNB)addition, release or modification procedures are almost transparent tothe mobile packet core network elements, such as the SAEGW 120, PCRF110, and OCS 115. That is, there is no signaling indication to themobile packet core to indicate whether the UE 160 is served by eitherthe 4G/LTE AN (that uses a first Radio Access Technology (RAT) type) orthe 5G/NR AN (that uses a second RAT type). This means that policy andcharging specific to RAT types cannot be applied. Presented herein aremethods to address this shortcoming using an in-band signaling approachin the User-Plane (UP).

A new in-band signaling is provided in the User-Plane, such as in theGeneral Packet Radio Service (GPRS)-User Plane (GTP-U) protocol, whichcan signal to the mobile packet core about the change in the AN. Thein-band signaling is used for exchanges between the eNB 172 and theSAEGW 120, between the gNB and the SAEGW 120, and between the eNB 172and gNB 182.

Reference is now made to FIGS. 2A and 2B for a description GTP-Uextension header provided to signal changes related to the AN for a UE.As shown in FIG. 2A, a new extension header “AN Change Notification” isprovided as part of GTP-U header 200 as set forth in 3GPP TS 29.281,where:

Octet-1: the ‘E’ bit 210 in the GTP-U extension header 200 is set to 1.

Octet-12: As shown at 220, a new Next Extension Header Type ‘AN ChangeNotification’=‘0011 0000’ i.e., 0x30 is introduced, as shown at 230,among a plurality of extension header field values 240 already defined.

Extension Header length: Set to 0x01

FIG. 2B shows another view of GTP-U extension header 200, including anextension header length 250, extension header content 260 and a nextextension header type 270. The extension header content 260 is used asan in-band flag to indicate the switching of bearers across ANs. Theflag may be of 8-bits in length.

Bits 0-3 (LSB) indicate the RAT Type such as E-UTRAN, NR etc.

Bits 4-6 (MSB) indicate the Cell group the AN belongs to, i.e., MasterCell Group (MCG) or Secondary Cell Group (SCG).

Bit 7 indicates the Split Bearer Flag.

This provides flexibility in applying policies specific to either cellgroup or RAT type. The assumption is that the S1-U end point does notchange with the RAT change. The extension headers may only be includedif there is a change in the RAT, and not included otherwise.

A new extension header context may be added to acknowledge the ANinformation change notification. For example, as shown in Table 1 below,a X111:1111 signals User Plane (UP) acknowledgment (ACK) of the ANchange notification.

TABLE 1 GTP-U Extension Header Content Cell Group (Bits 4-7) RAT (Bits0-3) Use XXXX 0000 Reserved XXXX 0001 4G XXXX 0010 5G-NR X000 XXXXReserved X001 XXXX Master Cell Group (MCG) X010 XXXX SCG (Secondary CellGroup) 1XXX XXXX ‘1’ Split Bearer Enabled ‘0’ Split Bearer Disabled X1111111 ACK (UP -> MeNB/SgNB)

FIGS. 3-5 show three flow diagrams that are part of an operational flowaccording to the techniques presented herein.

Turning to FIG. 3, a flow diagram is shown for a first part of anoperational flow. Here, the UE has attached to the 4G AN. FIG. 3 issimilar to FIG. 1 except that the SAEGW 120 is split into a controlplane part, referred to as SAEGW-C 122 and a user plane part, referredto as SAEGW-U 124. The control plane signaling is connected through theeNB 172 (Master Cell Group or MCG) of the 4G AN 170 as the UE 160 isbeing served by the eNB 172 at this time. The control plane signaling isshown at reference numeral 300 via the eNB 172, MME 130, SAEGW-C 122,PCRF 110 and OCS 115.

The user/data plane flow is shown at 310 between the UE 160, via the eNB172, SAEGW-U 124 and SAEGW-C 122. The AN components (e.g., eNB/gNB orvirtualized RAN components thereof) add the GTP-U extension header 200to the first data packet that would be relayed to the SAEGW-C 122 forfurther processing and triggering Gx and Gy Requests to the PCRF 110 andOCS 115, respectively. As shown in FIG. 3, the GTP-U extension header200 has the cell group (CG) set for MCG and the RAT set for 4G. Inaddition, the split bearer flag in the GTP-U extension header 200 is setto ‘0’. As a result, when the SAEGW-C 122 receives the first packet ofuser traffic associated with the UE 160, the SAEGW-C 122 does not act onthis packet as there is no change in the RAT. Instead, the SAEGW-C justdirects the packet to the SAEGW-U 124 for further processing, as shownat 320.

FIG. 4 shows a flow diagram for a second part of the operational flow.The UE 160 has moved to the 5G AN 180 and is now connected to the gNB182. In the 5G NSA Option-3X architecture, the eNB 172, called the MeNB,is still used for the S1-MME signaling. The control plane signaling isshown at reference numeral 400 via the eNB 172, MME 130, SAEGW-C 122,PCRF 110 and OCS 115.

In the user/data plane as shown at 410, the vRAN adds the GTP-Uextension header 200 to the first data packet that would be relayed tothe SAEGW-C 122 for further processing and triggering Gx and Gyrequests. The GTP-U extension header 200 now is configured with the CGset for the secondary group (SCG) and the RAT set for 5G. The splitbearer flag is still set to ‘0’. The SAEGW-C 122 detects that there is aRAT change and triggers the Gx and Gy to the PCRF 110 and OCS 115,respectively, so that Quota and Policy rules are applied for the trafficfor the UE 160 now based on its use of the 5G AN 180 instead of the 4GAN 170.

Reference is now made to FIG. 5. FIG. 5 shows a flow diagram for a thirdpart of the operational flow. The UE 160 has moved back to the 4G AN170. For example, the UE 160 has moved back from 5G to 4G coverage dueto unavailability of NR-RLC. However, as shown at 500, the control planesignaling anchor still remains with eNB 172 (Master eNB) only and thePDCP (S1-U) termination remains with the gNB 182 (Secondary gNB).

In the user/data plane, however, as shown at 510, the RAN networkelement (physical or virtual) adds the GTP-U extension header 200 to thefirst data packet that would be relayed to the SAEGW-C 122 for furtherprocessing and triggering Gx and Gy Requests. The GTP-U extension header200 has the CG set to MCG and the RAT set to 4G (a RAT change), and thesplit bearer flag set to ‘1’. In this scenario, since the user packet isserved by the LTE/e-UTRAN RLC, the PDCP/S1-U termination was with thegNB 182 (user packets are sent from the gNB 182 to the eNB 172 via theX2 interface, and then further to UE (in both uplink and downlinkdirections) using the LTE/E-UTRAN RLC via the eNB 172. The SAEGW-C 122detects that there is a RAT change (E-UTRAN in this case) and triggersthe Gx and Gy procedures. The PDCP termination would still remain at gNB182. The gNB 182 needs to know that the split bearer scenario hasoccurred, and the gNB 182 indicates it through the split bearer bit aswell as the CG field and RAT field set to MCG and 4G, respectively, inthe GTP-U extension header 200. The gNB 182 does this on GTP-U packetssent over the S1-U interface. The gNB 182 learns about this when theNR-RLC connectivity is lost and the X2-U interface is used between thegNB 182 and eNB 172. This is the only scenario in which the X2-Uinterface would be used and hence the gNB 182 can use this as a meansfor in-bang signaling about this split bearer indicator.

There are conditions in which the subscriber could be changing the RATbetween LTE and NR. In such cases there could be a temporary state wherethe PDCP and RLC anchor points are different. For example, the S1-Uinterface is used by the gNB 182 while the UE 160 is in LTE coverage andthe X2 interface is used for a data plane between the eNB 172 and thegNB 182.

The split bearer flag is enabled under such conditions, i.e., bit 7 inthe GTP-U extension header 200, as shown in FIG. 2B, is enabled. Oncethis condition is resolved to a single RAT and cell group, bit 7 in theGTP-U extension header 200 is disabled.

The SAEGW-C 122 can identify this flag and can set the RAT type alongthe Diameter interfaces either based on a static or dynamicconfiguration. A dynamic configuration could be based on clusteringalgorithms to classify the dominating RAT type during a split bearerscenario of DC NR Option-3X. Specifically, there is a possibility thatS1-U or PDCP termination is at gNB 182 and for user-data transmission atthe access side, it could use both the 5G NR RLC and also the 4G/EUTRANRLC (some portion of data could split on both access networks to meetthe bandwidth requirements). In such a case a dynamic configurationapproach may be useful to appropriately signal the dominating RAT typeto the packet core in order to apply the appropriate policy and chargingcriteria for the dominating RAT type. This is one of the possibilitieswithin 5G NSA Option-3X architecture.

FIG. 6 illustrates a detailed call flow 600 according to an exampleembodiment. The call flow 600 includes interactions with a HomeSubscriber Server (HSS) 190, not shown in previous figures. As shown at602, the UE 160 is DCNR capable and is connecting to the LTE radio ofthe eNB 172. At 604, the UE 160 sends a Non-Access Stratum (NAS) AttachRequest with the DCNR bit set as per 3GPP TS 23.401. Next, at 606, theeNB 172 receives the Attach Request and sends it to the MME 130 as per3GPP TS 23.401. At 608, the MME 130 and HSS 190 exchange anAuthentication Information Request and Response. Next, at 610, the MME130 sends to the SAEGW-C 122 a Create Session Request with RAT type setto eUTRAN, over the S11 interface, along with the Access Point Name(APN) and Quality of Service (QoS) parameters. At 612, the SAEGW-C 122initiates a Credit Control Request-Initial (CCR-I) message towards thePCRF 112, which in turn may receive policy rules to be applied to thesubscriber and specific to eUTRAN RAT type as a CCA-I. The PCRF 112 alsoarms the SAEGW-C 122 with the Event Trigger set to RAT_CHANGE asdescribed in 3GPP TS 29.212. At 614, the SAEGW-C 122 initiates a CCR-Itowards the OCS 114 if the Gy interface is enabled for quota management.

At 616, the Sx session is established between the SAEGW-C 122 andSAEGW-U 124. Configurations such as Packet Detection Rule (PDR),Forwarding Action Rule (FAR) and Usage Reporting Rule (URR) are appliedto the SAEGW-U 124. After the Sx session is established, the SAEGW-C 122sends a Create Session Response to the MME 130, at 618. The MME 130sends the Attach Accept to the UE 160 as a response with the GlobalUnique Temporary Identifier (GUTI) and allocated Internet Protocol (IP)address, at 620. The UE 160, at 622, sends an Attach Complete as anacknowledgement to the Attach Accept.

After the Attach Complete is sent to the MME 130, the UE 160, ifallocated with an IPv6 address, begins with the Router Solicitation andRouter Advertisement procedures with appropriate maximum transmit unit(MTU) values to be used in the data path. Up to this point the call flowfollows the 3GPP TS 23.401 standards.

At 624, the UE 160 sends data packets to the eNB 172. At 626, the eNB172 encapsulates the IP packets into GTP-U packets along with the GTP-UExtension Header 200 referred to above in connection with FIGS. 2A and2B. The Next Extension Header fields are set to the new value ‘0x30’i.e., AN Change Notification. The Extension Header 200 will have CellGroup set to ‘0001’, that of Master Cell group and RAT Type set to‘0001’ i.e., an indication of 4G as the access network serving theuser-data session. The GTP-U Extension Header 200 is sent on demand andin-band along the data plane i.e., the eNB 172 (or other applicable RANor vRAN component) includes extension headers only if there is a RAT orCell group change.

Though not specifically shown in FIG. 6, the SAEGW-U 124 sends anAcknowledgement to the eNB 172, again encoded in the GTP-U packet as anExtension Header in the downlink GTP-U packet, by setting bits 0-6 as‘1’.

At 628, the SAEGW-U 124, with GTP-U Extension Header encoded asdescribed herein, forwards the packet to the SAEGW-C 122 over the Sx-Uinterface to notify the control plane (SAEGW-C 122) about the RAT type.At 630, the SAEGW-C 122 determines whether there is a change in the RATtype and if so, appropriate Gx procedures are initiated to fetch RATspecific policies. In this case, the SAEGW-C 122 determines that thereis no change in the RAT as shown at 632, and hence processes the GTP-UExtension Header, and at 634, sends the data packet back to the SAEGW-Ualong the Sx-U to be forwarded further along the Gi path.

Until this point the UE 160 was in a 4G RAT. However, the UE 160, asshown at 636, the UE 160 now moves to a NR radio, gNB 182, also called aSecondary gNodeB (SgNB) which is associated as a Secondary Cell group tothe eNB 172 (called the MeNB). The UE 160 now sends data packets to thegNB 182, as shown at 638. When the UE 160 moves to gNB 182 (5G coveragein the EN-DC), there will be a secondary node addition procedure in theRLC and an Enhanced Radio Access Bearer (E-RAB) modification indicationprocedure triggered by the eNB. At this point, the S1-U PDCP terminationalso would be changed to the gNB 182 and the gNB 182 starts serving thedata session. In the user plane (and without using the GTP-U extensionheader presented herein), this would just be a change on the S1-U PDCPterminating point from one node to another (it is simply a GTP TunnelEndpoint Identifier (TEID) and IP address information change), but thatwould not indicate if it the change was from eNB to gNB or vice-versa).Thus, the next extension header in the GTP-U as described herein isprovided to carry exact RAT information to mobile packet core.

At 640, the gNB 182, or some appropriate vRAN component in a vRANimplementation, encapsulates IP packets within GTP-U packets with NextExtension Header. The Next Extension Header fields are set to the newvalue ‘0x30’ i.e., indicating the AN Change Notification. The GTP-UExtension Header shown in FIGS. 2A and 2B will have Cell Group set to‘0010’ for a Secondary Cell Group and RAT Type set to ‘0010’ for 5G-NR.The gNB 182 sends the GTP-U Extension Header 200 on demand and in-bandalong the data plane. That is, the gNB 182 includes extension headersonly if there is a RAT or Cell Group change. The SAEGW-U 124 sends tothe gNB 182 encoded in GTP-U extension header setting bits 0-6 as ‘1’ toacknowledge the information from the gNB 182.

At 642, the SAEGW-U 124 forwards the packet, with extension headersencoded in the GTP-U packet to the SAEGW-C 122 over the Sx-U interfaceto notify the control plane about the RAT type.

At 643, the SAEGW-C 122 determines whether there is a change in the RATtype and if so, appropriate Gx procedures are initiated to fetch RATspecific policies. At 644, after the SAEGW-C 122 processes the GTP-Upacket, the GTP-U packet is then sent back to the SAEGW-U 124 along theSx-U interface to be forwarded further along the Gi path. In this case,as there is a change in the RAT type, as determined by the SAEGW-C 122at 643, then at 646, the SAEGW-C initiates a Credit ControlRequest-Update (CCR-U) towards the PCRF 112 with Event Trigger set toRAT_CHANGE(2) as described in 3GPP TS 29.212. At 648, the PCRF 112responds with the RAT specific policies back to the SAEGW-C 122. TheSAEGW-C 122 then modifies the Sx session with specific FAR, PDR, URR andQuality of Service Enforcement Rule (QER).

Reference is now made to FIG. 7. FIG. 7 illustrates a detailed call flowfor the situation in which AN change notification reliability isindicated, along with acknowledgment by the user plane for in-bandsignaled AN information. As shown at 702, a DC NR capable UE 160 isunder the 4G coverage. At 704, the UE 160 successfully registers to thenetwork through an Attach sequence as described in 3GPP TS 23.401. Afterthe Attach Complete is sent to the MME (not shown in FIG. 7), the UE 160is allocated with an IPv6 address and begins the Router Solicitation andRouter Advertisement procedures with appropriate MTU values to be usedin the data path. The data packets are now transmitted from and to theUE, at 706, via eNB 172.

At 708(1), the eNB 172 encapsulates IP data packets the GTP-U NextExtension Header field enabled. The GTP-U Extension Header field isencoded to correctly reflect the RAT Type and Cell Group serving the UE160. The GTP-U Extension Header is sent on-demand and in-band to thedata plane.

The AN change notification due to RAT or Cell Group change are actionedonly by the core and nothing is sent to the RAN in return. However, tomaintain the consistency in states and reliability of notificationsbetween access networks and core network, an acknowledgement (ACK) isexpected from the core network component i.e., the SAEGW-U 124 towardsthe eNB 172 or gNB 182.

As shown at 708(1)-708(n), the eNB will continue to transmit the GTP-Upackets with the Extension Headers until it receives an acknowledgementfrom the SAEGW-U 124. The re-transmission of extension headers in theGTP-U packets means the encoding of extension headers are repeated inevery new user data packet. The packets GTP-U themselves are notretransmitted due to lack of acknowledgement. As shown at 710, theSAEGW-U 124 eventually sends an ACK to the eNB 172. The ACK from theSAEGW-U 124 to the eNB 172 stops further encoding of extension headersuntil the next RAT or Cell Group change.

At 712, the SAEGW-U 124 forwards the GTP-U packet to the SAEGW-C, if itwas not already done, to initiate appropriate Gx signaling procedures.In this case since there was no specific RAT change, Gx procedures forRAT changes may not be initiated. At 714, the SAEGW-C 122 processes theGTP-U packet and sends it sent back to the SAEGW-U 124 to be forwardedalong the SGi path.

As shown at 720, the UE 160 moves from 4G to 5G NR coverage. The radioand PDCP are served by the gNB 182, as explained above in connectionwith FIG. 5. The UE 160 sends a data packet to the gNB 182 when it movesto 5G NR coverage.

The gNB 182 encodes the GTP-U packet is with extension headers with RATType as 5G-NR and Cell Group as a Secondary Cell Group (SCG), and sendsthe encoded GTP-U packet to the SAEGW-U, as shown at 724(1). The gNB 182retransmits the GTP-U extension header until an ACK is received from theSAEGW-U, as shown at 724(2)-724(n). Eventually, as shown at 726, theSAEGW-U 124 sends an ACK towards the gNB 182 for the AN changenotification.

At 728, the SAEGW-U forwards the GTP-U packet to the SAEGW-C 122, if itwas not already done, to initiate appropriate Gx signaling procedures.In this case, since there is a RAT change, Gx procedures for RAT changesare initiated with Event Trigger set to RAT_CHANGE (2) requesting RATspecific policies, similar to operations 646 and 648 shown in FIG. 6.After the SAEGW-C 122 processes the GTP-U packet, the SAEGW-C 122 sendsit back to the SAEGW-U 124 to be forwarded along the SGi path.

Reference is now made to FIG. 8, for description of a method 800performed by a radio access network element (e.g., eNB, gNB or some vRANelement) in a radio access network, such as the second radio accessnetwork (arbitrarily chosen for purposes of this description. The methodis performed by the radio access network element in the context of acommunication system that includes at least a first radio access networkof a first radio access technology type and a second radio accessnetwork of a second radio access technology type. At 810, the methodincludes the radio access network element in the second radio accessnetwork receiving a data transmission from a user equipment that hasdual connectivity capabilities for communication in both the first radioaccess network and the second radio access network. At 820, the methodincludes the radio access network element determining whether there is achange in radio access technology type for the user equipment indicatingthat the user equipment has handed over from the first radio accessnetwork to the second radio access network. At 830, the method includesthe radio access network element, based on the determining operation820, encapsulating data from the user equipment in a packet thatincludes a header comprising an indication whether there is a change ofradio access network, to form an encapsulated packet. At 840, the methodincludes radio access network element sending the encapsulated packet toa mobile core network.

In one embodiment, the operation 830 of encapsulating may comprisesetting values in the header to indicate radio access technology typebeing either the first radio access technology type or the second radioaccess technology type, and a cell group being either a master cellgroup or a secondary cell group. Furthermore, in one form, when it isdetermined that the user equipment has changed radio access technologytype to the second radio access network from the first radio accessnetwork, the encapsulating operation 830 may include setting a value inthe header to indicate the change of radio access network, setting avalue in the header to indicate the radio access technology type is thesecond radio access technology type, and setting a value in the headerto indicate the cell group is the secondary cell group. As describedherein, in one form, the first radio access technology type is 4^(th)Generation (4G)/Long Term Evolution (LTE) and the second radio accesstechnology type is 5^(th) Generation (5G) New Radio (NR).

The method 800 may further include, in one form: at a radio accessnetwork element in the first radio access network: receiving a datatransmission from the user equipment; determining that the userequipment has handed over from the second radio access network back tothe second radio access network; and encapsulating data from the userequipment in a packet that includes a header comprising an indicationthat there is a change of radio access network, and an indication of theradio access technology type being the first radio access technologytype, an indication that the cell group is the master cell group, and aflag to indicate a split bearer scenario in which Packet DataConvergence Protocol (PDCP) termination is at the radio access networkelement in the second radio access network and data packets for the userequipment are sent from the radio access network element in the secondradio access network to the radio access network element in the firstradio access network for communication to the user equipment.

As described above in connection with FIGS. 2A and 2B, the header may bean extension header of a General Packet Radio Service (GPRS)-User Plane(GTP-U) protocol packet, and wherein the value in the header to indicatethe change of radio access network is a particular value in a GTP-U nextextension header field. The extension header may include a content fieldthat comprises one or more bits to represent the value for the radioaccess technology type, one or more bits to represent the value for thecell group, and a bit for the flag to indicate the split bearerscenario. In one form, wherein when it is determined that the userequipment has not changed radio access network, the encapsulatingoperation 830 may involve encapsulating the packet so as not to includethe extension header when forming the encapsulated packet.

As described above in connection with FIG. 7, the method 800 may furtherinclude repeating sending to the mobile core network encapsulatedpackets with the header comprising the indication of the change of radioaccess network until an acknowledgment is received from the mobile corenetwork to the change in radio access network.

Reference is now made to FIG. 9 for a description of a method 900performed by a gateway element (e.g., SAEGW-C 122 or SAEGW-U 124referred to in the figures above) in a mobile core network. The mobilecore network is in communication with at least a first radio accessnetwork of a first radio access technology type and a second radioaccess network of a second radio access technology type. At 910, themethod includes the gateway element obtaining an encapsulated packetrepresenting a data transmission sent by a user equipment that has dualconnectivity capabilities for communication in both the first radioaccess network and the second radio access network. The encapsulatedpacket includes a header that indicates whether there is a change inradio access network for the user equipment.

At 920, the method includes the gateway element evaluating the header ofthe encapsulated packet.

At 930, the method includes the gateway element determining whetherthere is a change in radio access network for the user equipment basedon the evaluating operation 920.

At 940, the method includes the gateway element forwarding theencapsulated packet to a user plane entity in the mobile core network.

In one form, the header indicates the user equipment is connected to thefirst radio access network using the first radio access technology typeor is connected to the second radio access network using the secondradio access technology type, and a cell group is either a master cellgroup or a secondary cell group.

Further, when it is determined that there is a change in radio accessnetwork, the method 900 may further include: sending to a policy andcharging rules function a credit control request update based on changein radio access technology type to either the first radio accesstechnology type or the second radio access technology type, as indicatedin the header; and receiving from the policy and charging rules functiona credit control request update response that specifies one or morepolicies, for the user equipment, for either the first radio accesstechnology type or the second radio access technology type.

As described above in connection with FIGS. 2A and 2B, the header may bean extension header of a General Packet Radio Service (GPRS)-User Plane(GTP-U) protocol packet, and wherein a value in the header to indicatethe change of radio access network is a particular value in a GTP-U nextextension header field. The extension header may include a content fieldthat comprises one or more bits to represent the value for the radioaccess technology type, one or more bits to represent the value for acell group as either a master cell group or a secondary cell group, anda bit for a flag to indicate a split bearer scenario.

In summary, techniques are provided to inform a mobile packet core ofthe (AN/RAT) change from LTE to NR and vice-versa with the use ofin-band signaling along the User-Plane and hence reduce S1-AP signalingbetween an eNB and MME. A new GTP-U extension header content (e.g., of 1byte) is provided to signal the AN/RAT information, Cell Group changesand acknowledging the same (mobile core network user plane to MeNB orSgNB) is also provided, implementing the reliability of notificationsfor these procedures. Further still, a method is provided to handle ANchange notification for split bearer scenarios (FIG. 5) by introducing asplit bearer flag for the mobile packet core to be notified of thepredominant access type serving the subscriber data session in 5G NSAOption-3, Option-3A and Option-3X, so that static or dynamicconfigurations can be applied by the mobile core network accordingly.

Referring to FIG. 10, a hardware block diagram is provided of acomputing device 1000 that may perform functions associated withoperations described herein in connection with the FIGS. 1-9. In variousembodiments, a computing device, such as computing device 1000 or anycombination of computing devices 1000, may be configured as anyentity/entities as discussed for the techniques depicted in connectionwith FIGS. 1-9 in order to perform operations of the various techniquesdiscussed herein.

In at least one embodiment, the computing device 1000 may include one ormore processor(s) 1002, one or more memory element(s) 1004, storage1006, a bus 1008, one or more network processor unit(s) 1010interconnected with one or more network input/output (I/O) interface(s)1012, one or more I/O interface(s) 1014, and control logic 1020. Invarious embodiments, instructions associated with logic for computingdevice 1000 can overlap in any manner and are not limited to thespecific allocation of instructions and/or operations described herein.

In at least one embodiment, processor(s) 1002 is/are at least onehardware processor configured to execute various tasks, operationsand/or functions for computing device 1000 as described herein accordingto software and/or instructions configured for computing device 1000.Processor(s) 1002 (e.g., a hardware processor) can execute any type ofinstructions associated with data to achieve the operations detailedherein. In one example, processor(s) 1002 can transform an element or anarticle (e.g., data, information) from one state or thing to anotherstate or thing. Any of potential processing elements, microprocessors,digital signal processor, baseband signal processor, modem, PHY,controllers, systems, managers, logic, and/or machines described hereincan be construed as being encompassed within the broad term ‘processor’.

In at least one embodiment, memory element(s) 1004 and/or storage 1006is/are configured to store data, information, software, and/orinstructions associated with computing device 1000, and/or logicconfigured for memory element(s) 1004 and/or storage 1006. For example,any logic described herein (e.g., control logic 1020) can, in variousembodiments, be stored for computing device 1000 using any combinationof memory element(s) 1004 and/or storage 1006. Note that in someembodiments, storage 1006 can be consolidated with memory element(s)1004 (or vice versa), or can overlap/exist in any other suitable manner.

In at least one embodiment, bus 1008 can be configured as an interfacethat enables one or more elements of computing device 1000 tocommunicate in order to exchange information and/or data. Bus 1008 canbe implemented with any architecture designed for passing control, dataand/or information between processors, memory elements/storage,peripheral devices, and/or any other hardware and/or software componentsthat may be configured for computing device 1000. In at least oneembodiment, bus 1008 may be implemented as a fast kernel-hostedinterconnect, potentially using shared memory between processes (e.g.,logic), which can enable efficient communication paths between theprocesses.

In various embodiments, network processor unit(s) 1010 may enablecommunication between computing device 1000 and other systems, entities,etc., via network I/O interface(s) 1012 to facilitate operationsdiscussed for various embodiments described herein. In variousembodiments, network processor unit(s) 1010 can be configured as acombination of hardware and/or software, such as one or more Ethernetdriver(s) and/or controller(s) or interface cards, Fibre Channel (e.g.,optical) driver(s) and/or controller(s), and/or other similar networkinterface driver(s) and/or controller(s) now known or hereafterdeveloped to enable communications between computing device 1000 andother systems, entities, etc. to facilitate operations for variousembodiments described herein. In various embodiments, network I/Ointerface(s) 1012 can be configured as one or more Ethernet port(s),Fibre Channel ports, and/or any other I/O port(s) now known or hereafterdeveloped. Thus, the network processor unit(s) 1010 and/or network I/Ointerface(s) 1012 may include suitable interfaces for receiving,transmitting, and/or otherwise communicating data and/or information ina network environment.

I/O interface(s) 1014 allow for input and output of data and/orinformation with other entities that may be connected to computer device1000. For example, I/O interface(s) 1014 may provide a connection toexternal devices such as a keyboard, keypad, a touch screen, and/or anyother suitable input and/or output device now known or hereafterdeveloped. In some instances, external devices can also include portablecomputer readable (non-transitory) storage media such as databasesystems, thumb drives, portable optical or magnetic disks, and memorycards. In still some instances, external devices can be a mechanism todisplay data to a user, such as, for example, a computer monitor, adisplay screen, or the like.

In various embodiments, control logic 1020 can include instructionsthat, when executed, cause processor(s) 1002 to perform operations,which can include, but not be limited to, providing overall controloperations of computing device; interacting with other entities,systems, etc. described herein; maintaining and/or interacting withstored data, information, parameters, etc. (e.g., memory element(s),storage, data structures, databases, tables, etc.); combinationsthereof; and/or the like to facilitate various operations forembodiments described herein.

The programs described herein (e.g., control logic 1020) may beidentified based upon application(s) for which they are implemented in aspecific embodiment. However, it should be appreciated that anyparticular program nomenclature herein is used merely for convenience;thus, embodiments herein should not be limited to use(s) solelydescribed in any specific application(s) identified and/or implied bysuch nomenclature.

[ow] In various embodiments, entities as described herein may storedata/information in any suitable volatile and/or non-volatile memoryitem (e.g., magnetic hard disk drive, solid state hard drive,semiconductor storage device, random access memory (RAM), read onlymemory (ROM), erasable programmable read only memory (EPROM),application specific integrated circuit (ASIC), etc.), software, logic(fixed logic, hardware logic, programmable logic, analog logic, digitallogic), hardware, and/or in any other suitable component, device,element, and/or object as may be appropriate. Any of the memory itemsdiscussed herein should be construed as being encompassed within thebroad term ‘memory element’. Data/information being tracked and/or sentto one or more entities as discussed herein could be provided in anydatabase, table, register, list, cache, storage, and/or storagestructure: all of which can be referenced at any suitable timeframe. Anysuch storage options may also be included within the broad term ‘memoryelement’ as used herein.

Note that in certain example implementations, operations as set forthherein may be implemented by logic encoded in one or more tangible mediathat is capable of storing instructions and/or digital information andmay be inclusive of non-transitory tangible media and/or non-transitorycomputer readable storage media (e.g., embedded logic provided in: anASIC, digital signal processing (DSP) instructions, software[potentially inclusive of object code and source code], etc.) forexecution by one or more processor(s), and/or other similar machine,etc. Generally, memory element(s) 1004 and/or storage 1006 can storedata, software, code, instructions (e.g., processor instructions),logic, parameters, combinations thereof, and/or the like used foroperations described herein. This includes memory element(s) 1004 and/orstorage 1006 being able to store data, software, code, instructions(e.g., processor instructions), logic, parameters, combinations thereof,or the like that are executed to carry out operations in accordance withteachings of the present disclosure.

In some instances, software of the present embodiments may be availablevia a non-transitory computer useable medium (e.g., magnetic or opticalmediums, magneto-optic mediums, CD-ROM, DVD, memory devices, etc.) of astationary or portable program product apparatus, downloadable file(s),file wrapper(s), object(s), package(s), container(s), and/or the like.In some instances, non-transitory computer readable storage media mayalso be removable. For example, a removable hard drive may be used formemory/storage in some implementations. Other examples may includeoptical and magnetic disks, thumb drives, and smart cards that can beinserted and/or otherwise connected to a computing device for transferonto another computer readable storage medium.

Variations and Implementations

Embodiments described herein may include one or more networks, which canrepresent a series of points and/or network elements of interconnectedcommunication paths for receiving and/or transmitting messages (e.g.,packets of information) that propagate through the one or more networks.These network elements offer communicative interfaces that facilitatecommunications between the network elements. A network can include anynumber of hardware and/or software elements coupled to (and incommunication with) each other through a communication medium. Suchnetworks can include, but are not limited to, any local area network(LAN), virtual LAN (VLAN), wide area network (WAN) (e.g., the Internet),software defined WAN (SD-WAN), wireless local area (WLA) access network,wireless wide area (WWA) access network, metropolitan area network(MAN), Intranet, Extranet, virtual private network (VPN), Low PowerNetwork (LPN), Low Power Wide Area Network (LPWAN), Machine to Machine(M2M) network, Internet of Things (IoT) network, Ethernetnetwork/switching system, any other appropriate architecture and/orsystem that facilitates communications in a network environment, and/orany suitable combination thereof.

Networks through which communications propagate can use any suitabletechnologies for communications including wireless communications (e.g.,4G/5G/nG, IEEE 802.11 (e.g., Wi-Fi®/Wi-Fib®), IEEE 802.16 (e.g.,Worldwide Interoperability for Microwave Access (WiMAX)),Radio-Frequency Identification (RFID), Near Field Communication (NFC),Bluetooth™, mm.wave, Ultra-Wideband (UWB), etc.), and/or wiredcommunications (e.g., T1 lines, T3 lines, digital subscriber lines(DSL), Ethernet, Fibre Channel, etc.). Generally, any suitable means ofcommunications may be used such as electric, sound, light, infrared,and/or radio to facilitate communications through one or more networksin accordance with embodiments herein. Communications, interactions,operations, etc. as discussed for various embodiments described hereinmay be performed among entities that may directly or indirectlyconnected utilizing any algorithms, communication protocols, interfaces,etc. (proprietary and/or non-proprietary) that allow for the exchange ofdata and/or information.

Communications in a network environment can be referred to herein as‘messages’, ‘messaging’, ‘signaling’, ‘data’, ‘content’, ‘objects’,‘requests’, ‘queries’, ‘responses’, ‘replies’, etc. which may beinclusive of packets. As referred to herein and in the claims, the term‘packet’ may be used in a generic sense to include packets, frames,segments, datagrams, and/or any other generic units that may be used totransmit communications in a network environment. Generally, a packet isa formatted unit of data that can contain control or routing information(e.g., source and destination address, source and destination port,etc.) and data, which is also sometimes referred to as a ‘payload’,‘data payload’, and variations thereof. In some embodiments, control orrouting information, management information, or the like can be includedin packet fields, such as within header(s) and/or trailer(s) of packets.Internet Protocol (IP) addresses discussed herein and in the claims caninclude any IP version 4 (IPv4) and/or IP version 6 (IPv6) addresses.

To the extent that embodiments presented herein relate to the storage ofdata, the embodiments may employ any number of any conventional or otherdatabases, data stores or storage structures (e.g., files, databases,data structures, data or other repositories, etc.) to store information.

Note that in this Specification, references to various features (e.g.,elements, structures, nodes, modules, components, engines, logic, steps,operations, functions, characteristics, etc.) included in ‘oneembodiment’, ‘example embodiment’, ‘an embodiment’, ‘anotherembodiment’, ‘certain embodiments’, ‘some embodiments’, ‘variousembodiments’, ‘other embodiments’, ‘alternative embodiment’, and thelike are intended to mean that any such features are included in one ormore embodiments of the present disclosure, but may or may notnecessarily be combined in the same embodiments. Note also that amodule, engine, client, controller, function, logic or the like as usedherein in this Specification, can be inclusive of an executable filecomprising instructions that can be understood and processed on aserver, computer, processor, machine, compute node, combinationsthereof, or the like and may further include library modules loadedduring execution, object files, system files, hardware logic, softwarelogic, or any other executable modules.

It is also noted that the operations and steps described with referenceto the preceding figures illustrate only some of the possible scenariosthat may be executed by one or more entities discussed herein. Some ofthese operations may be deleted or removed where appropriate, or thesesteps may be modified or changed considerably without departing from thescope of the presented concepts. In addition, the timing and sequence ofthese operations may be altered considerably and still achieve theresults taught in this disclosure. The preceding operational flows havebeen offered for purposes of example and discussion. Substantialflexibility is provided by the embodiments in that any suitablearrangements, chronologies, configurations, and timing mechanisms may beprovided without departing from the teachings of the discussed concepts.

As used herein, unless expressly stated to the contrary, use of thephrase ‘at least one of’, ‘one or more of’, ‘and/or’, variationsthereof, or the like are open-ended expressions that are bothconjunctive and disjunctive in operation for any and all possiblecombination of the associated listed items. For example, each of theexpressions ‘at least one of X, Y and Z’, ‘at least one of X, Y or Z’,‘one or more of X, Y and Z’, ‘one or more of X, Y or Z’ and ‘X, Y and/orZ’ can mean any of the following: 1) X, but not Y and not Z; 2) Y, butnot X and not Z; 3) Z, but not X and not Y; 4) X and Y, but not Z; 5) Xand Z, but not Y; 6) Y and Z, but not X; or 7) X, Y, and Z.

Additionally, unless expressly stated to the contrary, the terms‘first’, ‘second’, ‘third’, etc., are intended to distinguish theparticular nouns they modify (e.g., element, condition, node, module,activity, operation, etc.). Unless expressly stated to the contrary, theuse of these terms is not intended to indicate any type of order, rank,importance, temporal sequence, or hierarchy of the modified noun. Forexample, ‘first X’ and ‘second X’ are intended to designate two ‘X’elements that are not necessarily limited by any order, rank,importance, temporal sequence, or hierarchy of the two elements. Furtheras referred to herein, ‘at least one of’ and ‘one or more of can berepresented using the’(s)′ nomenclature (e.g., one or more element(s)).

In summary, in one form, a method is provided for use in a communicationsystem that includes at least a first radio access network of a firstradio access technology type and a second radio access network of asecond radio access technology type, the method performed at a radioaccess network element of the second radio access network, comprising:receiving a data transmission from a user equipment that has dualconnectivity capabilities for communication in both the first radioaccess network and the second radio access network; determining whetherthere is a change in radio access technology type for the user equipmentindicating that the user equipment has handed over from the first radioaccess network to the second radio access network; based on thedetermining, encapsulating data from the user equipment in a packet thatincludes a header comprising an indication whether there is a change ofradio access network, to form an encapsulated packet; and sending theencapsulated packet to a mobile core network.

In another form, an apparatus is provided comprising: a networkinterface configured to enable network communications in a communicationsystem that includes at least a first radio access network of a firstradio access technology type and a second radio access network of asecond radio access technology type; a processor coupled to the networkinterface, the processor configured to perform operations including:obtaining a data transmission from a user equipment that has dualconnectivity capabilities for communication in both the first radioaccess network and the second radio access network; determining whetherthere is a change in radio access technology type for the user equipmentindicating that the user equipment has handed over from the first radioaccess network to the second radio access network; based on thedetermining, encapsulating data from the user equipment in a packet thatincludes a header comprising an indication whether there is a change ofradio access network, to form an encapsulated packet; and sending theencapsulated packet, via the network interface, to a mobile corenetwork.

In still another form, one or more non-transitory computer readablestorage media are provided, encoded with instructions that, whenexecuted by at least one processor, cause the at least one processor toperform operations including: receiving a data transmission from a userequipment that has dual connectivity capabilities for communication inboth a first radio access network and a second radio access network;determining whether there is a change in radio access technology typefor the user equipment indicating that the user equipment has handedover from the first radio access network to the second radio accessnetwork; based on the determining, encapsulating data from the userequipment in a packet that includes a header comprising an indicationwhether there is a change of radio access network, to form anencapsulated packet; and sending the encapsulated packet to a mobilecore network.

In still another form, a method is provided that is performed in amobile core network that is in communication with at least a first radioaccess network of a first radio access technology type and a secondradio access network of a second radio access technology type, themethod performed at a gateway element in the mobile core network,comprising: obtaining an encapsulated packet representing a datatransmission sent by a user equipment that has dual connectivitycapabilities for communication in both the first radio access networkand the second radio access network, the encapsulated packet including aheader that indicates whether there is a change in radio access networkfor the user equipment; evaluating the header of the encapsulatedpacket; determining whether there is a change in radio access networkfor the user equipment based on the evaluating; and forwarding theencapsulated packet to a user plane entity in the mobile core network.

In another form, an apparatus is provided comprising: a networkinterface configured to enable network communications in a communicationsystem that includes at least a first radio access network of a firstradio access technology type and a second radio access network of asecond radio access technology type; and a processor coupled to thenetwork interface, the processor configured to perform operationsincluding: obtaining an encapsulated packet representing a datatransmission sent by a user equipment that has dual connectivitycapabilities for communication in both the first radio access networkand the second radio access network, the encapsulated packet including aheader that indicates whether there is a change in radio access networkfor the user equipment; evaluating the header of the encapsulatedpacket; determining whether there is a change in radio access networkfor the user equipment based on the evaluating; and forwarding theencapsulated packet to a user plane entity in the mobile core network.

Further still, one or more non-transitory computer readable storagemedia are provided, encoded with instructions that, when executed by atleast one processor, cause the at least one processor to performoperations including: obtaining an encapsulated packet representing adata transmission sent by a user equipment that has dual connectivitycapabilities for communication in both the first radio access networkand the second radio access network, the encapsulated packet including aheader that indicates whether there is a change in radio access networkfor the user equipment; evaluating the header of the encapsulatedpacket; determining whether there is a change in radio access networkfor the user equipment based on the evaluating; and forwarding theencapsulated packet to a user plane entity in the mobile core network.

One or more advantages described herein are not meant to suggest thatany one of the embodiments described herein necessarily provides all ofthe described advantages or that all the embodiments of the presentdisclosure necessarily provide any one of the described advantages.Numerous other changes, substitutions, variations, alterations, and/ormodifications may be ascertained to one skilled in the art and it isintended that the present disclosure encompass all such changes,substitutions, variations, alterations, and/or modifications as fallingwithin the scope of the appended claims.

What is claimed is:
 1. In a communication system that includes at leasta first radio access network of a first radio access technology type anda second radio access network of a second radio access technology type,a method performed at a radio access network element of the second radioaccess network, comprising: receiving a data transmission from a userequipment that has dual connectivity capabilities for communication inboth the first radio access network and the second radio access network;determining whether there is a change in radio access technology typefor the user equipment indicating that the user equipment has handedover from the first radio access network to the second radio accessnetwork; based on the determining, encapsulating data from the userequipment in a packet that includes a header comprising an indicationwhether there is a change of radio access network, to form anencapsulated packet; and sending the encapsulated packet to a mobilecore network.
 2. The method of claim 1, wherein based on thedetermining, encapsulating further comprises setting values in theheader to indicate radio access technology type being either the firstradio access technology type or the second radio access technology type,and a cell group being either a master cell group or a secondary cellgroup.
 3. The method of claim 2, when it is determined that the userequipment has changed radio access technology type to the second radioaccess network from the first radio access network, encapsulatingcomprises setting a value in the header to indicate the change of radioaccess network, setting a value in the header to indicate the radioaccess technology type is the second radio access technology type, andsetting a value in the header to indicate the cell group is thesecondary cell group.
 4. The method of claim 3, further comprising: at aradio access network element in the first radio access network:receiving a data transmission from the user equipment; determining thatthe user equipment has handed over from the second radio access networkback to the second radio access network; and encapsulating data from theuser equipment in a packet that includes a header comprising anindication that there is a change of radio access network, and anindication of the radio access technology type being the first radioaccess technology type, an indication that the cell group is the mastercell group, and a flag to indicate a split bearer scenario in whichPacket Data Convergence Protocol (PDCP) termination is at the radioaccess network element in the second radio access network and datapackets for the user equipment are sent from the radio access networkelement in the second radio access network to the radio access networkelement in the first radio access network for communication to the userequipment.
 5. The method of claim 4, wherein the header is an extensionheader of a General Packet Radio Service (GPRS)-User Plane (GTP-U)protocol packet, and wherein the value in the header to indicate thechange of radio access network is a particular value in a GTP-U nextextension header field.
 6. The method of claim 5, wherein the extensionheader includes a content field that comprises one or more bits torepresent the value for the radio access technology type, one or morebits to represent the value for the cell group, and a bit for the flagto indicate the split bearer scenario.
 7. The method of claim 1, whereinthe header is an extension header, and wherein when it is determinedthat the user equipment has not changed radio access network,encapsulating comprises encapsulating the packet so as not to includethe extension header when forming the encapsulated packet.
 8. The methodof claim 1, wherein the first radio access technology type is 4^(th)Generation (4G)/Long Term Evolution (LTE) and the second radio accesstechnology type is 5^(th) Generation (5G) New Radio (NR).
 9. The methodof claim 1, further comprising: repeating sending to the mobile corenetwork encapsulated packets with the header comprising the indicationof the change of radio access network until an acknowledgment isreceived from the mobile core network to the change in radio accessnetwork.
 10. In a mobile core network that is in communication with atleast a first radio access network of a first radio access technologytype and a second radio access network of a second radio accesstechnology type, a method performed at a gateway element in the mobilecore network, comprising: obtaining an encapsulated packet representinga data transmission sent by a user equipment that has dual connectivitycapabilities for communication in both the first radio access networkand the second radio access network, the encapsulated packet including aheader that indicates whether there is a change in radio access networkfor the user equipment; evaluating the header of the encapsulatedpacket; determining whether there is a change in radio access networkfor the user equipment based on the evaluating; and forwarding theencapsulated packet to a user plane entity in the mobile core network.11. The method of claim 10, wherein the header indicates the userequipment is connected to the first radio access network using the firstradio access technology type or is connected to the second radio accessnetwork using the second radio access technology type, and a cell groupis either a master cell group or a secondary cell group.
 12. The methodof claim 11, when it is determined that there is a change in radioaccess network, further comprising: sending to a policy and chargingrules function a credit control request update based on change in radioaccess technology type to either the first radio access technology typeor the second radio access technology type, as indicated in the header;and receiving from the policy and charging rules function a creditcontrol request update response that specifies one or more policies, forthe user equipment, for either the first radio access technology type orthe second radio access technology type.
 13. The method of claim 10,wherein the header is an extension header of a General Packet RadioService (GPRS)-User Plane (GTP-U) protocol packet, and wherein a valuein the header to indicate the change in radio access network is aparticular value in a GTP-U next extension header field.
 14. The methodof claim 13, wherein the extension header includes a content field thatcomprises one or more bits to represent the value for the radio accesstechnology type, one or more bits to represent the value for a cellgroup as either a master cell group or a secondary cell group, and a bitfor a flag to indicate a split bearer scenario.
 15. An apparatuscomprising: a network interface configured to enable networkcommunications in a communication system that includes at least a firstradio access network of a first radio access technology type and asecond radio access network of a second radio access technology type;and a processor coupled to the network interface, the processorconfigured to perform operations including: obtaining a datatransmission from a user equipment that has dual connectivitycapabilities for communication in both the first radio access networkand the second radio access network; determining whether there is achange in radio access technology type for the user equipment indicatingthat the user equipment has handed over from the first radio accessnetwork to the second radio access network; based on the determining,encapsulating data from the user equipment in a packet that includes aheader comprising an indication whether there is a change of radioaccess network, to form an encapsulated packet; and sending theencapsulated packet, via the network interface, to a mobile corenetwork.
 16. The apparatus of claim 15, wherein the processor isconfigured to perform encapsulating by setting values in the header toindicate radio access technology type being either the first radioaccess technology type or the second radio access technology type, and acell group being either a master cell group or a secondary cell group.17. The apparatus of claim 16, wherein when the processor determinesthat the user equipment has changed radio access technology type to thesecond radio access network from the first radio access network, theprocessor performs the encapsulating by setting a value in the header toindicate the change of radio access network, setting a value in theheader to indicate the radio access technology type is the second radioaccess technology type, and setting a value in the header to indicatethe cell group is the secondary cell group.
 18. The apparatus of claim15, wherein the header is an extension header, and wherein when theprocessor determines that the user equipment has not changed radioaccess network, the processor performs the encapsulating so as not toinclude the extension header when forming the encapsulated packet. 19.The apparatus of claim 15, wherein the first radio access technologytype is 4^(th) Generation (4G)/Long Term Evolution (LTE) and the secondradio access technology type is 5^(th) Generation (5G) New Radio (NR).20. The apparatus of claim 15, wherein the processor is furtherconfigured to perform: repeating sending to the mobile core networkencapsulated packets with the header comprising the indication of thechange of radio access network until an acknowledgment is received fromthe mobile core network to the change in radio access network.